In situ hydraulic borehole mining equipment and techniques are known in the art and are the subject of patents that disclose systems for the mining of uranium, phosphate and heavy oil resource bodies, such as U.S. Pat. No. 4,915,452 issued to Dibble; U.S. Pat. No. 4,296,970 issued to Hodges; and U.S. Pat. No. 4,348,058 issued to Coakley et al. However, the mining systems and methods in these representative disclosures do not effectively address the fluid dynamics associated with maximizing effective jet horsepower, do not provide an economical alternative for mining in an isolated flooded environment, and do not effectively address the ability to efficiently lift a subterranean resource to the surface. More specifically, these prior patents disclose equipment systems designed solely to lift ore back to the surface by the use of a high-pressure eduction system. Notwithstanding the advances made by these inventions, to date, no prior art hydraulic mining system has attained commercial success of the shortcomings being attributable to the ineffective and inefficient utilization of fluids and the sub-optimization of the mining extraction processs. Prior art systems do not fully integrate the critical components of water jet borehole mining to optimize reach and production rates on the one hand and to minimize energy consumption on the other. Thus, continual economically justifiable and sustainable commercial production rates have not been achieved, and the operating costs of prior art borehole mining systems are too high to effectively replace conventional commercial mining systems and techniques.
In addition to the foregoing, the very mining pipe associated with prior art mining systems is the source of frustrating and costly operational problems. The threaded portions used to couple various sections of the mining pipe are prone to galling and eventually become unusable. In a threaded connection with multiple telescoping pipes, several sets of threads must be properly aligned in order to make up the mining string. Even with small misalignments, threads become galled, rendering a piece of mining pipe unusable. With the three concentric parallel strings of the subject invention, the pipe is aligned and threaded together with only one pipe, preferably, the outermost pipe, while the other two pipes employ tapered coupling or connecting portions, which self-align, virtually eliminating any chance of damaging the mining pipe sections. With the threaded connections and tapered internal pipes of the system invention, the problem of galling of threads is eliminated, inasmuch as the threads interconnecting all but the outermost section have been eliminated.
Another problem associated with prior art mining systems is the tendency of the systems to collect oversized particles in the bottom of the mining cavity. These particles clog up the system. When the system becomes blocked, advancement stops, requiring tripping out of the hole and drilling the rock fragments up by conventional methods. This interruption, which is eliminated by the system disclosed herein, severely affects operating economics and completely stops advancement under block caving conditions.
Water jet borehole mining has several advantages over conventional mining techniques. One of the key attributes exploited through the borehole mining technique is the ability to selectively target and mine high-grade resources. With water jet borehole mining, the highest-grade section of the resources can be selectively mined while leaving the remaining lower grade resources in place. With traditional mining techniques, the overburden is removed or worked around in order to access the targeted resource. The usual expense and dilution of the economics of the project can render the project economically unfeasible. The use of the subject invention and associated techniques allows a small borehole to be drilled into the resource body, thereby permitting the target ore to be efficiently and economically mined and moved to surface without disturbing the overburden. Non-turbid lamination of the water flow to the jet is one component of the subject invention in terms of ultimate production and reach of the jet in the cavern in both atmospheric and submerged conditions.
The environmental impact of an underground hydraulic borehole mining process is exponentially less than that of a conventional open pit mining application. Highly mobile equipment deployable at any angle on commercially available modern drilling rigs allows high accessibility to horizontal surface based, high slope and marine based applications. Small-scale equipment used in the process minimizes site impact and decreases mining risk of groundwater and surface contamination by cased isolation of the mining system and effective protection of groundwater. Leaching of resources such as uranium or contaminated fluids or acids such as those generated through oil sands or heavy minerals mining is minimized, if not completely eliminated. A unique aspect of the system herein disclosed is that, compared to prior art systems, it can operate both in a fully submerged state and in an atmospheric state. Operating in an atmospheric state extends the reach in certain geology by increasing net delivered horsepower at the rock face.
In some cases, total elimination of open pit access allows safe access to the resource. The effective mining of the resource can allow stripping the target components within the ore, such as the ablation of U308 particles from sandstone or stripping target minerals from mineral sands and the corresponding reinjection of the waste tails in situ by blended sealing with cementitious grout. Effectively, remediation costs and requirements are significantly reduced, less overburden is moved, less in situ groundwater is affected, less surface impact is created and the carbon footprint of mining operations using the invention is greatly reduced compared to conventional mining operations or prior art hydraulic borehole mining technology. Personnel head count can be reduced and exposure to high-risk ore such as uranium can be greatly reduced by effective and economic commercial hydraulic borehole mining. It is not necessary to expose personnel to radiation risk underground. Moreover, the invention provides closed loop fluid circulation, thereby limiting oxygenation of the resource, and reducing environmental exposure of radiation, salt water and acid onto the surface and in situ mining sector.
Within the United States and in multiple countries around the world a vast inventory of projects exist that have either reached the end of their known economic mining life, or that cannot be initiated into production due to unachievable economics or operational or technical inaccessibility. This invention with the complete modernization of new, conceptual and proven hydraulic engineering components will provide a new opportunity to reestablish prior mined resource areas, to create new jobs by economic resource creation and to enrich both private industry and government owned resource bases. Further, this invention will allow the establishment of a new realm of mining potential in environmentally sensitive areas which are not accessible currently because of destructive surface mining or risk of exposure to undesirable mining circumstances. Additionally, the mobility and accessibility of this invention allows the resource owner to target smaller reserves with more discerning accuracy of mining, thereby increasing established resource and reducing capital and regional impact.
Resource body types exist that are not currently available, such as metallurgical coal seams in steeply dipping planes along the environmentally sensitive slope of the Rockies, the steep hills of Appalachia, and the ultra-heavy oil reserves of west Texas and California. The shale oil reserves on the Eastern Rockies slopes are sub-economic to conventional mining. The deep in situ uranium deposits in New Mexico, Colorado and Texas and the kaolin and phosphate deposits of the Southeastern states all have development, reserve and resource potential beneficial to private industry and government with the effective deployment of this system and apparatus. The Kimberlite reserves of Saskatchewan, Canada cannot be developed with conventional mining methods, yet exist as the largest Kimberlite reserves in the world. Kimberlite pipes which only allow fractional accessibility through conventional mining, Kimberlite and Lamprolite pipes in Australia and South Africa that have reached economic limit because dewatering costs are too high or the size of the pipes and the incline of the hanging walls are too steep for conventional mining, all may be accessed by the system and methods herein disclosed. The same may be said of millions of tons of other known resources that cannot be mined or declared as economic reserves because the ore is inaccessible due to high water tables and or excessively steep access ramps. This invention allows the resource owner to drill deep into pipes and target high-grade ores and minerals selectively and, under certain conditions, up to depths never achievable with conventional mining techniques. Offshore mining of granular resources such as tin can be in situations where conventional dredges cannot access the resource through deep overburden. Technical accessibility to otherwise unavailable resources with the system of the present invention significantly enhances mining potential while simultaneously offering low surface and environmental disturbance.
In the hydrocarbon resource sector, the system allows further development of oil shales, oil sands, oil rock and gas shales by cavity creation. Cavity creation allows significant opening of the natural fractures of the rock and may be used as a replacement to hydraulic fracturing or “fracking.” This advancement alone may have a significant impact on the conventional oil industry in areas where fracking creates potential for disturbance or is completely banned.
The nature of the system allows the operator to excavate the oil in situ and transport the oil bearing rock to the surface. The subject invention will allow unique access to depleting fields that have significant quantities of oil not currently economically recoverable with known technology. The mining system of the present invention could be used in countries where fracking is completely banned and as a substitute where shallow heavy oil deposits exist.